Commenter "thedemonhog" brought up an important distinction between heavily serialized shows and shows that also have a lot of complex mythology (like Lost). And commenter "Vincent" presupposed that DVD sales for serialized shows ought to be much better than for procedurals.

So it looks like there is something to be said for the correlation between serialized drama and DVD sales. How to explain The Office? One commenter, "Jrock" suggests that part of the popularity of The Office was that it is pretty serialized, at least as far as 30 minute sitcoms go. "The Jim and Pam love story had a great “hook” that kept viewers wanting more..."